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Molecular structure, configurational entropy and viscosity of silicate melts: Link through the Adam and Gibbs theory of viscous flow

Le Losq, Charles; Neuville, Daniel R.

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The Adam and Gibbs theory depicts the viscous flow of silicate melts as governed by the cooperative re-arrangement of molecular sub-systems. Considering that such subsystems involve the silicate Qn units (n = number of bridging oxygens), this study presents a model that links the Qn unit fractions to the melt configurational entropy at the glass transition temperature Tg, Sconf(Tg), and finally, to its viscosity η. With 13 adjustable parameters, the model reproduces η and Tg of melts in the...[Show more]

dc.contributor.authorLe Losq, Charles
dc.contributor.authorNeuville, Daniel R.
dc.date.accessioned2021-08-11T01:33:53Z
dc.identifier.issn0022-3093
dc.identifier.urihttp://hdl.handle.net/1885/243867
dc.description.abstractThe Adam and Gibbs theory depicts the viscous flow of silicate melts as governed by the cooperative re-arrangement of molecular sub-systems. Considering that such subsystems involve the silicate Qn units (n = number of bridging oxygens), this study presents a model that links the Qn unit fractions to the melt configurational entropy at the glass transition temperature Tg, Sconf(Tg), and finally, to its viscosity η. With 13 adjustable parameters, the model reproduces η and Tg of melts in the Na2O-K2O-SiO2 system (60 ≤ [SiO2] ≤ 100 mol%) with 1σ standard deviations of 0.18 log unit and 10.6°, respectively. The model helps understanding the links between the melt chemical composition, structure, Sconf and η. For instance, small compositional changes in highly polymerized melts generate important changes in their Sconf(Tg) because of an excess of entropy generated by mixing Si between Q4 and Q3 units. Changing the melt silica concentration affects the Qn unit distribution, this resulting in non-linear changes in the topological contribution to Sconf(Tg). The model also indicates that, at [SiO2] ≥ 60 mol%, the mixed alkali effect has negligible impact on the silicate glass Qn unit distribution, as corroborated by Raman spectroscopy data on mixed Na-K tri- and tetrasilicate glasses. Such model may be critical to link the melt structure to its physical and thermodynamic properties, but its refinement requires further high-quality quantitative structural data on silicate and aluminosilicate melts
dc.description.sponsorshipThis study was supported by Australian Research Council grant FL130100066 to Hugh St. C. O′Neill.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherElsevier
dc.rights© 2017 Elsevier B.V.
dc.sourceJournal of Non-crystalline Solids
dc.subjectViscosity
dc.subjectEntropy
dc.subjectGlass
dc.subjectMelt
dc.subjectSilicate
dc.subjectRaman spectroscopy
dc.titleMolecular structure, configurational entropy and viscosity of silicate melts: Link through the Adam and Gibbs theory of viscous flow
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume463
dc.date.issued2017
local.identifier.absfor030606 - Structural Chemistry and Spectroscopy
local.identifier.ariespublicationa383154xPUB5565
local.publisher.urlhttps://www.elsevier.com/en-au
local.type.statusPublished Version
local.contributor.affiliationLe Losq, Charles, College of Science, ANU
local.contributor.affiliationNeuville, Daniel R., CNRS-IPGP, Sorbonne Paris Cite
local.description.embargo2099-12-31
dc.relationhttp://purl.org/au-research/grants/arc/FL130100066
local.bibliographicCitation.startpage175
local.bibliographicCitation.lastpage188
local.identifier.doi10.1016/j.jnoncrysol.2017.02.010
dc.date.updated2020-11-23T10:50:18Z
local.identifier.scopusID2-s2.0-85015284409
local.identifier.thomsonID000405154700025
CollectionsANU Research Publications

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